Administration of endotoxin to humans allows a unique way to evaluate the early inflammatory reactions that occur during infection. Characterizing these responses, and the mechanisms that control them, is important because these inflammatory responses contribute to the development of septic shock and organ failure. Few data are available describing the effects of acute inflammation covered by endotoxin on respiratory drive and frequency. This information may have implications for the development of respiratory failure during sepsis.We have previously shown that intravenous (IV) endotoxin leads to a loss of heart rate variability and an increase in heart rate regularity, as reflected by a decrease in approximate entropy and power spectra. Similar analyses of respiratory frequency will be performed in subjects given either IV endotoxin alone or endotoxin with ibuprofen, using respiratory inductive plethysmography to monitor breathing patterns, respiratory drive, frequency, and muscle strength. In subjects given ibuprofen, symptoms and fever do not develop but similar hemodynamic responses to endotoxin remain. This information will link data relating to hemodynamic and respiratory responses to endotoxin in humans.Subjects are no longer being enrolled. Data analysis is being performed.